1. Field of the Invention
The present invention relates to a technique of synthesizing or blending several video data. In particular, the present invention relates to video data processing apparatus and method, which have improvement in time base correction between several video data.
2. Description of the Related Art
There has been conventionally known a technique of synthesizing several video data. In many cases, first and second video data thus synchronized are a video data including a synchronizing signal having the same frequency inherently. Moreover, the following method is given as a technique of multiplexing a still image, that is, the second video data to the first video data as a moving image. According to the method, the second video data (e.g., OSD signal) is multiplexed after read from a memory (see JPN. PAT. APPLN. KOKAI Publication No. 2002-165018). In this case, the read timing of the second video data is preset to a predetermined timing of the first video data. It is presumed that the first and second video data are reproduced using a hardware circuit.
In the display area of a moving image, that is, main video image, the following display is desired in order to obtain various and plentiful expressions. More specifically, the main video image is displayed in a state that a second video image is matched thereto as a time zone event. For example, screen effect is desired such that the moving image, that is, main video image is matched to the second video image to change each transmittance of the main and second video images. Moreover, if the main video image is a motion picture (movie), it is desired to display translated texts in synchronous with the movie character's words.
In this case, the following matter should be considered. More specifically, the second video image has a video source reproduced using software, and not a video source processed using hardware like the conventional case. If the video source of the second video image is reproduced using the software, the reproduction time depends on a reference clock of a computer. Therefore, a frame rate of the second video image does not necessarily match with that of the main video image reproduced using another hardware. There is no problem so long as the second video image reproduced using the software is simply framed and displayed in a rectangular area of part of the moving image, that is, the main video image regardless of a change of the main video image.
However, there has not been disclosed a technique of closely relating display contents of main and second video images, and synchronizing the frame rates of the both.